基底刚度影响仰拱混凝土疲劳损伤的试验研究  

Experimental study on influence of tunnel bed stiffness to fatigue damage characteristics of invert concrete

作　　者：刘宁[1] 彭立敏[1] 施成华[1] Liu Ning Peng Limin Shi Chenghua(School of Civil and Engineering, Central South University, Changsha 410075, China)

机构地区：[1]中南大学土木工程学院,湖南长沙410075

出　　处：《华中科技大学学报（自然科学版）》2016年第12期31-37,共7页Journal of Huazhong University of Science and Technology(Natural Science Edition)

基　　金：国家自然科学基金-煤炭联合基金资助项目(U1361204);国家自然科学基金资助项目(51278494)

摘　　要：为探明铁路隧道基底刚度对仰拱混凝土疲劳损伤的影响,研制了一种可变换基底刚度并模拟仰拱力学环境的加载装置,结合MTS疲劳试验机进行了仰拱混凝土疲劳损伤的试验研究,揭示了静动载耦合作用下隧道仰拱混凝土的疲劳损伤机理,构建了引入抗力系数的仰拱混凝土疲劳损伤计算模型,阐明了基底刚度对仰拱混凝土动态应变特征及疲劳损伤的影响程度.结果表明:隧道基底刚度对仰拱混凝土疲劳损伤和累积应变增长影响显著;随着基底刚度的降低,混凝土动应变及损伤值快速增长并发生疲劳破坏;混凝土损伤演化曲线与动应变曲线相似,均具有明显的三阶段变化特征;基于疲劳损伤拟合公式和抗力系数表达式,量化了基底刚度对混凝土疲劳损伤的影响程度;均布弹簧基底有利于混凝土抗疲劳性能的提高,其疲劳寿命约为三点弯折条件下混凝土疲劳寿命的10倍.To explore the influence of bedrock stiffness of railway tunnel on the fatigue damage char-acteristics of invert concrete ,for the simulation of invert mechanical environmental ,a new device with different bed stiffness were designed in our experiments .Through the experimental research of the in-vert concrete damage combined the MTS fatigue testing machine ,the evolution of the damage mecha-nism of invert concrete due to both static and cyclic load was revealed .By introducing the resistance coefficient ,a fatigue damage model relating the parameter was proposed .The dynamic strain and fa-tigue damage characteristics of invert concrete were deduced under different bed stiffness .The results show that the bed stiffness has a significant effect on the damage grow th ratio and strain increment of TIC .With the decrease of bed stiffness ,the damage and strain of invert concrete increases and fatigue failure occurs . The curve of fatigue damage evolution and the curve dynamic strain are in similar shape ,which could describe three phases of change characteristics .With the interpolation formula of concrete damage and the R-N curve expressions analyzed ,an experimental parameter was given and redefined to quantify the effect of bed stiffness ,and the impact of bed stiffness on the concrete damage was also quantified .It is found that the fatigue life of concrete in a uniform environment is higher than 10 times of the concrete under three point bending condition .

关 键 词：铁路隧道 仰拱混凝土 动态应变 疲劳损伤 基底刚度 

分 类 号：U25[交通运输工程—道路与铁道工程]